Welcome.
It is possible to have both... some doctors say commonly, while others say rarely! so who knows what to believe!

While there is rapid cycling BP, BP moods tend to be longer and not as related to what is happening in your life. For example being really depressed for absolutely no reason.

Regardless, the drugs for BP help BPD (but to a lesser extent than BP) and the therapy for BPD certainly helps BP (to a lesser extent than in BPD).

So taking meds and going to therapy would be a really great move even if it is BPD alone. Even if you do have BP, you are unlikely to achieve complete remission with meds because of the BPD but it would definitely help.

Just my thoughts, but I'm not a doctor so best to talk with your pdoc about your options